FR2921582A1 - INSTALLATION FOR BLOWING CONTAINERS IN THERMOPLASTIC MATERIAL - Google Patents

Abstract

Installation (1) for blowing, using a fluid under pressure, containers from blanks (2), made of thermoplastic material and comprising a body (3) and a neck (6), said installation comprising a mold (5) for blowing with a cavity (4) for molding, in which the body (3) of a blank (2) can be placed, said mold (5) having an upper surface (7) of which is adapted to protrude the neck (6) of a blank (2), once the body (3) of said blank (2) placed in said cavity (4), said installation (1) also comprising a nozzle (8) with an end (9) shaped to be in sealed functional relation with the collar (6) of the projecting blank (2), characterized in that said nozzle end (9) is secured to means ( 12) for degassing the blowing fluid able to bear tightly on the upper surface (7) of the mold (5) forming a volume (13) int laughing wherein the pressurized blowing fluid blown into the preform (2) is adapted to be evacuated after the preform blow-molding operation (2).

Description

INSTALLATION FOR BLOWING CONTAINERS IN THERMOPLASTIC MATERIAL

The present invention generally relates to the field of the manufacture of containers made of thermoplastic material, such as PET or PEN, by a process of blowing or stretch-blow molding from a blank (such as preform or intermediate container), and more specifically concerns improvements made to the blowing installations, using a fluid under pressure, containers from blanks of thermoplastic material whose body is enclosed in a mold of blowing and which have been previously heated in a thermal conditioning furnace, said installations comprising a nozzle comprising an end shaped to be in sealed functional relation with the neck of the blank.

In known manner, the nozzle is arranged to be movable, in all or part, axially above the blow mold between a raised position or raised position in which the nozzle is not functional (opening and closing of the mold for loading a roughing and unloading of the molded container) and a low position or blowing position in which the end of the nozzle cooperates sealingly with the neck of the blank, or with the face of the mold above which protrudes the neck of the blank and wherein the nozzle is functional.

Blowing installations are known in which the end of the nozzle, in the operative position, cooperates positively with the neck of the blank and is either abutted sealingly against the rim (edge) of the neck of the blank, or is tightly fitted in or on the neck of the blank.

Blowing systems are also known in which the end of the nozzle is shaped bell-shaped larger than the neck of the blank and caps the latter by bearing frontally, sealingly against the face of the mold on which the collar of the blank protrudes (see for example the document FR 2 764 544).

A blowing sequence normally comprises a pre-blowing phase of the blank using a fluid (generally air) at a mean pressure (for example 12 × 05 Pa), then a blowing phase proper. under high pressure (for example 40 x 105 Pa) generally accompanied by mechanical axial stretching by means of a drawing rod, and finally an exhaust phase with evacuation of the pre-blowing / blowing air. It is known from the prior art, and in particular from document FR 2 872 082, in the name of the Applicant, to provide a blowing installation comprising several solenoid valves for the selective connection of said nozzle, and for which three sequentially controls respective solenoid valves which, on the one hand, are respectively connected to a medium pressure fluid source, a high pressure fluid source and an exhaust and which, on the other side, are connected to the nozzle.

However, the control system of the exhaust by a solenoid valve 20 adds a control complexity of the blowing process and increases the manufacturing costs of such a blowing installation.

It is indeed necessary to provide means for exhausting the fluid blown under pressure at the end of the blowing cycle, as this may result in a loud slamming during this exhaust which, in addition to the problems of noise pollution, may damage the fluid. blowing installation and the container that has just been blown.

It would therefore be particularly advantageous to provide a blowing installation to eliminate the use of a solenoid valve for the exhaust of the blowing fluid, which would reduce the manufacturing costs of such an installation while reducing the risk of malfunction of the exhaust of the blowing fluid.

According to a first of its aspects, the present invention relates to an installation for blowing, using a fluid under pressure, containers from blanks, made of thermoplastic material and comprising a body and a neck, said installation comprising a blow mold with a molding cavity, in which is able to be placed the body of a blank, the mold having an upper surface of which is able to project the neck of a blank, once the body of said blank placed in the cavity, the installation also comprising a nozzle with an end shaped to be in sealed functional relation with the neck of the projecting blank, installation characterized in that the nozzle end is secured to degassing means blowing fluid adapted to bear tightly on the upper surface of the mold forming an interior volume in which the blowing fluid blown so The pressure in the blank is able to be evacuated after the operation of blowing the blank.

It is thus formed degassing means of the fluid blown under pressure in the blank does not require the control of an additional solenoid valve and also does not require the passage of the exhaust fluid through the blowing nozzle, resulting in a lengthening the total time of the blowing process of a container, which limits the rate of blowing of such an installation.

Advantageously, the degassing means are provided surrounding the nozzle end.

Advantageously, the degassing means are in the form of a body coaxial with the blowing axis of the nozzle around the nozzle end. According to a first advantageous embodiment of the degassing means, said degassing means are in the form of a bell surrounding the end of the nozzle and opening directed towards the upper surface of the mold. According to a second advantageous embodiment of the degassing means, said degassing means are in the form of a body comprising a substantially cylindrical central section sealingly surrounding the nozzle end and a substantially planar radial ring having means protruding sealing able to come into sealing engagement on the upper surface of the mold, thanks to which the internal volume of the degassing means is delimited by the radial ring, the sealing means and the upper surface of the mold.

In order to form a tight internal sealed volume, the degassing means comprise sealing means able to bear on the upper surface of the mold in the form of a sealing skirt made of an elastic material, such as rubber or polyurethane. In order to control the formation of the internal volume as a function of the sealed connection of the nozzle, the degassing means are able to be moved axially with the aid of control means.

Advantageously, the control means are in the form of a cam and a roller adapted to move on the cam.

According to a second advantageous embodiment of the degassing means, said degassing means are in the form of a jack.

In order to allow the blowing mold to be cooled, exhaust ducts are provided opening into the upper surface of the blowing mold, whereby the degassed blowing fluid of the blown container is discharged from the interior of the degassing means. passing through said exhaust channels of the blow mold.

In order to allow the silent exhaust of the blowing fluid, the exhaust ducts are provided on one side opening into the internal volume of the degassing means, and on the other side in an annular channel to which is connected a duct. exhaust of the blowing fluid comprising a silencer device.

In order to allow uniform cooling of the blow mold, the exhaust channels are regularly dug in the blow mold concentrically to the blow axis of the nozzle.

According to a second of its aspects, the present invention relates to a method of blowing using a fluid under pressure of containers from blanks, made of thermoplastic material and comprising a body and a neck, the body of a blank being adapted to be placed in a mold cavity of a blow mold belonging to a blow-molding installation, said installation also comprising a blowing nozzle having an end shaped to be in sealed functional relation with the neck of a blank projecting from an upper surface of the mold, the method being characterized in that it comprises at least the following steps of: placing the blank in the blow mold; Sealing solidification of the blowing nozzle with the neck of the blank; Blowing of the blank; Watertight separation of the nozzle from the neck of the blown container; Degassing the blowing fluid in a closed interior volume formed around the neck of the container projecting from the upper surface of the blowing mold; Exhaust of the blowing fluid to the outside from the closed interior volume; Transfer of the blown container out of the blow mold.

Advantageously, the method according to the invention comprises an additional step of passing the degassed fluid through exhaust channels formed in the blow mold, before said step of exhausting the fluid to the outside.

Advantageously, the method comprises a step of forming said closed interior volume by displacement of a body coaxial with the blowing nozzle adapted to bear tightly on the upper surface of the mold.

The present invention is now described with the aid of examples which are only illustrative and in no way limitative of the scope of the invention, and from the following illustrations, in which: FIG. 1 is a diagrammatic view in axial section of a first embodiment of a blowing installation according to the invention, and Figure 2 is also a schematic view in axial section of a second embodiment of a blowing installation according to the invention.

In the remainder of the description, the term "blank" is understood to mean a hollow body which is either in the form of a preform, that is to say of a substantially axial tubular element with a closed end and an open end presenting the final shape of the neck of the container to be blown, an intermediate container, that is to say a preform that has been pre-blown, but must undergo a new blowing operation.

It is shown in Figure 1 in an axial sectional view of a first embodiment of a blowing installation 1 according to the invention.

In a manner known per se, the blowing installation 1 allows the blowing of containers from blanks 2 of thermoplastic material, preferably preforms preheated in a thermal conditioning furnace, each blank 2 comprising a body 3 adapted to be enclosed in a mold cavity 4 of a blow mold 5, and a neck 6 adapted to protrude from an upper surface 7 of the mold 5, said installation 1 comprising a blowing nozzle 8 comprising an end 9 (or nose of nozzle) shaped to be in sealed functional relation with the neck 6 of the draft 2 protruding, that is to say by either by direct contact of the end 9 of the nozzle with the rim of the neck of the blank (The nozzle is then of the contacting drinking type), or by sealingly pressing a bell surrounding the neck 6 of the blank 2 on the upper surface 7 of the mold 5.

The term "upper" as used in the present description only refers to the direction of representation of the blowing installation 1 in the figures, and should in no way be understood as limiting the scope of the invention to this invention. only embodiment.

The blowing nozzle 8 internally has an internal cavity 10 in which is able to move axially an elongation rod 11 (when it is present) in order to allow the drawing of the blank 2 at the time of blowing, the downward movement of the rod 11 inside the blowing cavity 4 being synchronized with the blowing of fluid under pressure inside the blank 2 placed in the mold 5.

The end 9 of the nozzle 8 is secured to means 12 for degassing the blowing fluid able to bear tightly on the upper surface 7 of the mold 5 and forming an internal volume 13 in which the blowing fluid is blown under pressure in the blank 2 is able to be evacuated after the blowing operation of the blank 2. It is thus formed a closed volume 13 in which the pressurized fluid can relax, with a view to its escape. There is thus formed an intermediate exhaust of the pressurized fluid blown before its escape to the atmosphere, and which does not require the control of a solenoid valve.

Preferably, the inner volume 13 is formed at the periphery of the neck 6 projecting from the upper surface 7.

More specifically, the degassing means 12 are provided around the nozzle end 9 and are in the form of a body 14 coaxial with the X-X blowing axis of the nozzle 8.

According to a first embodiment of the degassing means 12 according to the invention, and as illustrated in FIG. 1, the degassing means 12 are in the form of a bell 15 surrounding the end 9 of the nozzle 8 and opening towards the upper surface 7 of the mold 5.

Alternatively, and according to a second embodiment of the degassing means 12 according to the invention, and as illustrated in FIG. 2, the degassing means 12 are in the form of a body 16 comprising a section 17, substantially cylindrical, sealingly surrounding the end 9 of the nozzle 8 and a substantially planar radial ring 18 having projecting sealing means 19 adapted to bear tightly on the upper surface 7 of the mold 5 thanks to which the internal volume 13 of the degassing means 12 is delimited by the radial crown 18, the sealing means 19 and the upper surface 7 of the mold 5.

More precisely, according to the embodiment illustrated in FIG. 2, the sealing means 19 are in the form of a protrusion or sealing skirt 20 provided at the periphery of the radial crown 18 of the central body 16 of the means 12 of FIG. degassing. The radial ring 18 is provided integral with the end 9 of the nozzle 8 so that the ring 18 is not in contact with the upper surface 7 of the mold 5 thus forming a closed volume 13 during the implementation. sealing contact 19 sealing means on this upper surface 7.

According to the two embodiments of the degassing means 12, these comprise means 19, 21 for sealing able to bear on the upper surface 7 of the mold 5 in the form of a sealing skirt 20 made in a resilient material, such as rubber or polyurethane, and allowing the formation of a sealed volume 13 when the sealing means 19, 21 are brought into sealing contact on the upper surface 7 of the mold 5.

In order to allow the control of the descent of the degassing means 12 in the direction of the mold 5 independently of the downward movement of the blast nozzle 8, the degassing means 12 are able to be moved axially by means 22 control, for example in the form of a cam 23 and a roller 24 able to move on the cam 23, or in the form of a jack.

According to one possible embodiment of the control means 22, the rolling roller 24 may be provided at the end of a rod 25 directly attached to an external lateral surface of the degassing means 12, for example on the external lateral surface the bell 15 (see Figure 1), or on the outer lateral surface 27 of the central section 17 (see Figure 2).

According to the first embodiment of the degassing means 12, once the fluid under pressure has been expanded in the internal volume 13 formed by the bell 15, it is provided, in order to evacuate the fluid towards the atmosphere, either to form recesses in the circumferential wall of the bell 15, either to fix an air exhaust device 27 on the peripheral outer peripheral surface of the bell 15 through which the air expanded in the inner volume 13 can flow and to escape quietly to the atmosphere.

Alternatively, and always in order to allow the exhaust of the expanded air into the internal volume 13 of the degassing means, it is possible to provide exhaust channels 28 which are provided opening into the upper surface 7 of the mold 5 of blowing, thanks to which the degassed blowing fluid of the blown container is discharged from the internal volume 13 of the degassing means 12 through said channels 28 for exhausting the blowing mold 5, which at the same time makes it possible to cool blow mold 5, because of the expansion of the pressurized fluid in these channels 28. The mold 5 has indeed tend to heat up because of contacting, at the time of blowing, the hot thermoplastic material blown against the internal wall of the molding cavity 4.

The exhaust channels 28 are provided on one side opening into the internal volume 13 of the degassing means 12, and on the other side in an annular channel 29 on which is connected a conduit 30 for exhausting the blowing fluid comprising at the end of the duct 30, a device 31 with a silent exhaust, of a type known per se, which allows the discharge of the blowing fluid to the atmosphere after it has relaxed in the interior volume and the channels 28 exhaust.

In order to cool the entire mold 5 as evenly as possible, the exhaust channels 28 are regularly dug in the blow mold 5 concentrically with the X-X blowing axis of the nozzle 8.

According to an advantageous embodiment, the annular channel 29 is formed in the bottom 32 of the blow mold 5.

According to a second of its aspects, the present invention also relates to a method of blowing with a fluid under pressure of containers from blanks 2, made of thermoplastic material and comprising a body 3 and a neck 6, the body 3 of a blank 2 being capable of being placed in a mold cavity 4 of a blow mold 5 belonging to a blow-molding installation 1, said installation 1 also comprising a blowing nozzle 8 having an end 9 shaped to being in sealed functional relationship with the neck 6 of a blank 2 projecting from an upper surface 7 of the mold 5, the method being characterized in that it comprises at least the following steps of: Placing the blank 2 in the blow mold 5; Sealing tightness of the blowing nozzle 8 with the neck 6 of the blank 2; Blowing of the blank 2; Watertight separation of the nozzle 8 from the neck 6 of the blown container; Degassing of the blowing fluid in a closed internal volume 13 formed around the neck 6 of the container projecting from the upper surface 7 of the blowing mold 5; Exhaust of the blowing fluid to the outside from the inner volume 13 closed; Transfer of the blown container out of the blow mold.

In addition, according to one possible embodiment, the method comprises an additional step of passing the degassed fluid through exhaust channels 28 formed in said blow mold 5 prior to said step of exhausting the fluid to the outside. (that is to say towards the atmosphere).

Similarly, the method comprises a step of forming said closed internal volume 13 by displacement of a body 14, 16 coaxial with said blowing nozzle 8 able to bear tightly on the upper surface 7 of the mold 5.

Claims (8)

1. Installation (1) for blowing, using a fluid under pressure, containers from blanks (2), made of thermoplastic material and comprising a body (3) and a neck (6), said installation comprising a blow molding mold (5) with a molding cavity (4), in which the body (3) of a blank (2) can be placed, said mold (5) having an upper surface (7) of which is able to protrude the neck (6) of a blank (2), once the body (3) of said blank (2) placed in said cavity (4), said installation (1) also comprising a nozzle (8). ) with an end (9) shaped to be in sealed functional relation with the neck (6) of the blank (2) projecting, installation characterized in that said end (9) of the nozzle (8) is secured to means (12) for degassing the blowing fluid able to bear tightly on the upper surface (7) of the mold (5) by forming a volume (13) i nterieur in which the blowing fluid blown under pressure in the blank (2) is able to be evacuated after the blowing operation of the blank (2). 2. Installation according to claim 1, characterized in that said means (12) for degassing are provided surrounding said end (9) nozzle (8). 3. Installation according to any one of the preceding claims, characterized in that said means (12) for degassing are in the form of a body (14) coaxial with the axis (XX) of blowing said nozzle (8). ) blowing around said nozzle end (9) (8). 4. Installation according to any one of the preceding claims, characterized in that said means (12) for degassing are in the form of a bell (15) surrounding said 5. 5 10 15 6. 20 7. 25 8.309.extremity (9) of said nozzle (8) and opening directed towards said upper surface (7) of said mold (5). Installation according to any one of claims 1 or 2, characterized in that said means (12) for degassing are in the form of a body (16) comprising a substantially cylindrical central section (17) sealingly surrounding said end (9) nozzle (8) and a substantially planar radial ring (18) having projecting sealing means (19) able to bear tightly against said upper surface (7) of said mold (5), thanks to wherein said internal volume (13) of said degassing means (12) is delimited by said radial ring (18), said sealing means (19) and said upper surface (7) of said mold (5). Installation according to any one of the preceding claims, characterized in that said means (12) for degassing comprise means (19, 21) for sealing able to bear on said upper surface (7) of said mold (5) presenting in the form of a skirt (20) sealing made of an elastic material, such as rubber or polyurethane. Installation according to any one of the preceding claims, characterized in that said means (12) for degassing are able to be displaced axially by means (22) of control. Installation according to the preceding claim, characterized in that said means (22) for control are in the form of a cam (23) and a roller (24) bearing adapted to move on the cam (23). Installation according to claim 7, characterized in that said control means are in the form of a jack. 11. Installation according to the preceding claim, characterized in that said exhaust channels (28) are provided on one side opening into said internal volume (13) of said degassing means (12), and on the other side in an annular channel (29) to which is connected a conduit (30) for exhausting the blowing fluid comprising a device (31) with a silent exhaust. Installation according to claim 10 or 11, characterized in that said exhaust channels (28) are regularly hollowed in said blow mold (5) concentrically to the axis (X-X) blowing said nozzle (8). Method for blowing with a fluid under pressure of containers from blanks (2), made of thermoplastic material and comprising a body (3) and a neck (6), the body (3) of a blank (2) being able to be placed in a mold cavity (4) of a blow mold (5) belonging to a blowing installation (1), said installation (1) also comprising a blowing nozzle (8) having an end (9) shaped to be in sealed functional relation with the neck (6) of a blank (2) projecting from an upper surface (7) of said mold (5), the method being characterized in that it comprises at least the following steps of: placing the blank (2) in the blow mold (5); Sealing tightness of the blowing nozzle (8) with the neck (6) of the blank (2); Blowing of the blank (2); 10. Installation according to any one of the preceding claims, characterized in that channels (28) of exhaust are provided opening into said upper surface (7) of said mold (5) blowing, thanks to which the blowing fluid degassed from the blown container is evacuated from said volume (13) inside said degassing means (12) passing through said channels (28) for exhausting said blow mold (5). Sealed separation of the nozzle (8) from the neck (6) of the blown container; Degassing of the blowing fluid in a closed interior volume (13) formed around the neck (6) of the container projecting from the upper surface (7) of the blowing mold (5); Exhaust of the blowing fluid to the outside from the closed interior volume (13); Transfer of the blown container out of the blow mold (5). 14. Method according to the preceding claim, characterized in that it comprises an additional step of passage of the degassed fluid through the exhaust channels (28) formed in said blow mold (5), before said step of exhausting the fluid to the outside. 15. Method according to any one of claims 13 or 14, characterized in that it comprises a step of forming said volume (13) closed interior by displacement of a body (14, 16) coaxial with said nozzle (8) blowing device adapted to bear tightly on the upper surface (7) of the mold (5).